1. Field of the Invention
The present invention provides a method of forming a plurality of spaced, substantially parallel fractures from a deviated well bore, and more particularly, to such a method wherein fractures are extended in a subterranean formation from spaced fracture initiation points by applying hydraulic pressure to the formation via such initiation points.
2. Description of the Prior Art
In the production of hydrocarbons from subterranean rock formations penetrated by well bores, a commonly used technique for stimulating such production is to create and extend fractures in the formations. Most often, the fractures are created by applying hydraulic pressure to the subterranean formations from the well bores penetrating them. That is, a fracturing fluid is pumped through the well bore and into a formation to be fractured at a rate such that the resultant hydraulic pressure exerted on the formation causes one or more fractures to be created therein. The fractures are extended by continued pumping, and the fractures are either propped open by a propping agent, e.g., sand, deposited therein or the fracture faces are etched by a reactive fluid such as an acid whereby hydrocarbons contained in the formation readily flow through the fractures into the well bore.
The term "subterranean formation" is used herein to mean an entire subterranean rock formation bounded by formations formed of dissimilar rock materials or a hydrocarbon containing zone disposed within a larger rock formation.
Most fractures formed in formations by applying hydraulic pressure thereto lie in substantially vertical planes and extend outwardly from the well bore in a direction at right angles to the in situ least principal stress in the formation. When fractures are created from a substantially vertical well bore penetrating the formation, only two vertical fracture wings are often produced which extend from opposite sides of the well bore in a direction at right angles to the in situ least principal stress in the formation. This leaves a major portion of the formation without fractures, and less than a maximum hydrocarbon production increase is achieved.
In order to maximize the number of fractures created in a subterranean formation and the production of hydrocarbons therefrom, methods of creating a plurality of spaced, substantially parallel fractures from a single deviated well bore penetrating a formation have heretofore been developed and used. For example, U.S. Pat. No. 3,835,928 issued Sept. 17, 1974, discloses a method of forming a plurality of vertically disposed spaced fractures from a deviated well bore penetrating a formation. In accordance with that method, the deviated well bore is drilled in a direction transverse to a known preferred fracture orientation, spaced fracture initiation points are created in the deviated well bore, and spaced vertical fractures are produced in the formation by separately creating and extending a fracture from each fracture initiation point.
By the present invention an improved method of forming a plurality of spaced substantially parallel fractures from a single deviated well bore is provided.